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All About Wolves: Gray Wolves of Yellowstone

Wolf Families

A gray wolf from the Nez Perce pack in the acclimation pen prior to release Wolves are very social animals. They live and hunt together in groups called packs. A wolf pack is really just another name for a family of wolves. A pack is usually made up of an adult male and female wolf and their offspring of various ages. Pack sizes range from three to twenty wolves.

A wolf pack has a definite social structure and rules of conduct. The pack leaders are the alpha male and female. These two animals are dominant over all the other wolves in the pack. The alpha male and female are the only wolves that breed and produce pups in the pack, and they also get to eat first at kills.

Wolf pups are born in the spring after a gestation period of around 63 days. A female can have anywhere between one and nine pups, but the average litter size is four pups. The pups are born with their eyes closed and are totally helpless. Pups weigh about one pound at birth. The female stays in the den nursing and caring for her pups while the other pack members hunt and bring back food for her to eat.

A 4 or 5 week-old gray wolf pup at Yellowstone National Park Wolf pups grow very quickly. By the time their eyes open, 15 days after birth, they weigh four pounds. At three weeks they begin to play inside the den. Two weeks later they weigh 13 pounds and have begun wandering outside the den under the watchful eye of their mom. This is when their mother starts to wean them from milk. She and the other adult pack members start the pups on solid food by regurgitating semi-digested meat directly into their mouths or by depositing this food on the ground in front of the pups. When the pups get big enough the adults bring pieces of meat from their kills for the pups to eat. Between the ages of two and three months the pups leave their den permanently. Soon after this they begin traveling and hunting with the pack.

The social structure of the wolf pack changes from year to year. Wolves in the pack move up and down in the "pecking order" or hierarchy. A wolf lower down in the pecking order may challenge an alpha wolf for pack leadership. If the alpha wolf loses this challenge, it will likely go off on its own, find another mate, and start a new pack. Wolves very low in the pecking order (that are constantly picked on by the other pack members) may also leave the pack. They become lone wolves until they either form their own pack or on rare occasions join an existing wolf pack.

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